Manually operable circuit interrupter with automatic current overload protection

ABSTRACT

A motor circuit interrupter characterized by a manually operated fast-acting switch and a bi-metallic over-load relay for trip opening of the switch contacts in response to current overloads. The switch comprises means for moving electric contacts between open and closed positions which means includes a releasable arm which is movable between latched and unlatched positions. When in the &#39;&#39;&#39;&#39;unlatched&#39;&#39;&#39;&#39; condition, the contacts are open and the operating means cannot be operated to effect a re-closing of the contacts. The switch further comprises a pivoted latch lever operatively connected to the releasable arm to retain the arm in the latched condition, or for effecting unlatching of the arm, a latch retainer lever to retain the latch lever in the latch position said retainer lever is operatively connected to the trip plate of the overload relay to effect unlatching of the latch lever and releasable arm in response to an overload current. The retainer lever is spring-biased to the latch position with the latch lever and the retainer lever comprising an extension engageable with the latch lever when the latter is in the unlatched position to maintain the latch lever in a relatching position.

United States Patent 1191 Richards MANUALLY OPERAELE tItRCUlT PrimaryExaminer-Harold Broome Attorney, Agent, or FirmL. P. Johns 57 ABSTRACT Amotor circuit interrupter characterized by a manu- Dec. 30, 1975 allyoperated fast-acting switch and a bi-metallic overload relay for tripopening of the switch contacts in response to current overloads. Theswitch comprises means for moving electric contacts between open andclosed positions which means includes a releasable arm which is movablebetween latched and unlatched positions. When in the unlatched"condition, the contacts are open and the operating means cannot beoperated to effect a re-closing of the contacts. The switch furthercomprises a pivoted latch lever operatively connected to the releasablearm to retain the arm in the latched condition, or for effectingunlatching of the arm, a latch retainer lever to retain the latch leverin the latch position said retainer lever is operatively connected tothe trip plate of the overload relay to effect unlatching of the latchlever and releasable arm in response to an overload current. Theretainer lever is spring-biased to the latch position with the latchlever and the retainer lever comprising an extension engageable with thelatch lever when the latter is in the unlatched position to maintain thelatch lever in a relatching position.

5 Claims, 5 Drawing Figures US. Patent Dec. 30, 1975 Sheet 2 0f 2MANUALLY OPERABLE cIRcUIr INTERRUPTER WITH AUTOMATIC CURRENT OVERLOADPROTECTION CROSS-REFERENCE TO RELATED APPLICATIONS BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates to a circuitinterrupter having a switch tripping mechanism responsive to currentoverloads.

2. Description of the Prior Art Motor circuit interrupters of priorconstruction have been provided with current overload protective devicesthat function satisfactorily in response to abnormal currents such asovercurrents, ground fault currents, and short circuits, that occur inan electrical distribution system. Circuit interrupters of that typefunction satisfactorily for the purposes intended, but it is desirableunder some circumstances to also provide for currents in excess or belowthe rating of the heater elements selected for the motor to be'controlled. An interrupter for a given current rating may functionentirely satisfactorily in one location which is relatively close to thecurrent source, but function unsatisfactorily at a location which islocated at a considerable distance from that source. The variations incurrent are due to differences in efficiency and design of motors ratedat the same horsepower as produced by various manufacturers; and extentof voltage drop occurring in the feeder conductors from the voltagesupply source to the motor windings. Accordingly, it is desirable toprovide a motor circuit interrupter having adjustable overloadprotection adaptable to functioning satisfactorily for the motor currentspecifically encountered.

SUMMARY OF THE INVENTION It has been found in accordance with thisinventiop that the foregoing problem may be overcome by providing acircuit interrupter with adjustable overload protection which comprisesrelatively movable contact means and means releasable to effectautomatic opening of said contact means, operating means for moving thecontacts between open and closed positions, the operating meansincluding a releasable arm movable between latched and unlatchedpositions, a pivoted latch lever operable to effect latching orunlatching of the releasable arm, a latch retainer lever effective toreleasably retain the latch lever in the latched position; a tripmechanism comprising a trip plate, a position adjusted pivoted triplever, and bimetal means for actuating the latch retainer lever inresponse to excessive heat radiated to the bimetals by the heaterelements when subjected to current in excess of the rating of the heaterelements, the trip plate being operatively connected to the retainerlever to move the latch lever to the unlatched position, and the latchretainer lever being spring-biased in the latched position.

The advantage of the device of this invention is that a manuallyoperated toggle mechanism which provides switching control toalternately close and open electrical contacts is combined with anoverload relay and 2 provided with lever means associated with the relayfor positively tripping the switch in response to an overload current.

. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of athree-pole overload relay connected to a circuit interrupter inaccordance with this invention;

FIG. 2 is a vertical sectional view taken on the line II-II of FIG. 1,with the outer housing omitted;

FIG. 3 is a vertical sectional view taken on the line IIIIII of FIG. 2showing the trip mechanism in the reset position;

FIG. 4 is a vertical sectional view showing the trip mechanism in thetripped position; and

FIG. 5 is a vertical sectional view of the trip mechanism in a positionintermediate those of FIGS. 3 and 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT In FIG. 1 a circuit" interrupteris generally indicated at 7 and it comprises'a manually operated switch9 and an overload relay 11, both of which are mounted on a supportingbase 13.

Inasmuch as a detail description of the switch 9 is set forth in theapplication of Edward L. Richards, Ser. No. 404,579, filed Oct. 9, 1973,the description is limited to the parts that are essential to theoperation of the invention disclosed herein. Suffijce it to say theswitch 9 is a multi-pole, such as a three-pole, switch which includes apair of stationary contacts 17, a pair of movable contacts 19, as wellas movable contact carrier means 21. The switch 9 also comprises amanually operated over-center toggle mechanism generally indicated at 23which in turn comprises a releasable arm 25 that is pivotally mounted ona pivot pin 27 that extends between a pair of upright frames 29 and 31(FIG. 2). The overhead toggle mechanism 23 is enclosed within a housing33 of electrically insulating material and includes a handle 35 whichextends upwardly through the upper side of the housing.

As shown in FIG. 3 the right end of the releasable arm 25 is retained ina latched position by a trip mechanism which comprises a latch lever 37and a latch retainer lever 39. The latch lever 37 is an L-shaped orbellcrank type lever which is pivoted on a pair of similar trunnions 41extending from opposite sides thereof into corresponding apertures inspaced upright frames 29, 31. The latch lever 37 also includes anopening 43 in which the left end of the arm 25 is seated when in thelatched position as shown in FIG. 3. The lower end of the latch lever 37extends to and is engaged by the latch retainer lever 39 as shown inFIG. 3.

The latch retainer lever 39 is a substantially vertically extendingmember having similar trunnions 45 extending from opposite sides thereofand seated 'in corresponding apertures in the spaced upright frames 29,31. Hole 47 is disposed in the latch retainer lever 39 below thetrunnions 45 and outwardly extending lips 49 and 51 are provided at thelower and upper sides of the hole 47. The lower end portion of the latchretainer lever 37 is disposed in an aperture 53 of a trip plate 55 whichas shown in FIG. 1 extends from the overload relay 11. When the tripplate 55 is moved by the relay to the left as viewed in FIG. 3 the latchretainer lever 39 rotates clockwise until the lower extremity of thelatch retainer lever 37 moves out of the hole 47 and from the lip 49,whereupon the latch lever rotates counterclockwise in response to anupper pressure applied to the upper side of the opening 43 by thereleasable arm 25. The releasoccurs, the'heaters 73 cause the bi-metal71 to move able arm 25 moves until it strikes a stop pin 57 whichextends between the upright frames 29, 31. To mini- '3 mize frictionbetween the end of the arm 25 and the latch lever 37 a roller 59 ismounted on a pin 61 at the end of the arm. Movement of the retainerlever 39 and f latch lever 37 in the manner described constitutestripping of the current interrupter 9 and causes the movable contacts 19to separate from the stationary contacts 17 (FIG. 1).

The tripped position of the arm 25 is shown in FIG. 4 with the roller 59in contact with the pin 57 as well as in contact with the upper end ofthe latch lever 37 whereby the latch lever 37 is maintained in theposition shown. in FIG. 4. Thus the lower end of the lever is maintainedat a position below the hole 47, where it remains until such time as theswitch 9 is reset, the arm 25 is rotated counterclockwise about thepivot pin 27 until the roller 57 strikes a projection 63 on the leverand at the lower side of the opening 43. When the roller 59'strikes theprojection 63 it causes the lever to rotate counterclockwise until theleft end of the lever 37 isagain seated in the hole 47 of the retainerlever 39. The retainer lever 39 is biased counterclockwise by a wirespring 65 whereby it is normally urged against the lower end of thelatch lever 37.

.7 4 77-, and the trip plate 55. When a current in excess of that'forwhich the heater elements are rated to handle the crossbar 75 againstthe lower end of the trip lever 77 causing the upper end thereof torotate counterclockwise and pull the trip plate 55 to the left,whereupon the latch retainer lever 39 is rotated clockwise as i .1 setforth above.

In conclusion, the combination of the manual switch tripped voids thetoggle mechanism of the manual switch which assumes a non-operativetripped position.

The upper end of the opening 43 of the lever 37 is reinforced by aprojection 63 which engages the roller and provides a broader surfacefor contact therewith when the roller 59 is seated in the opening 43.The projection 63 includes a body portion 67a which is secured to thesurface of the latch lever 37 in a suitable manner such as spot welding.

In order to prevent the retainer lever 39 and the latch lever 37 frombecoming disposed in any undesirable position other than that shown inthe latch position of FIG. 3 and the unlatch position of FIG. 4 theupper end of the retainer lever 39 includes an extension 69 (FIG. 5)which is adapted to engage the side of the lever 37 or the projectionmember 67a when the arm 25 is moving either up or down during trippingor resetting of the switch 9. Thus, if an excessive force is appliedduring tripping or resetting the latch lever 37 and the retainer lever39 are maintained in the desired positions with respect to each other asshown in FIGS. 3 and 4.

Inasmuch as the overload relay is disclosed specifically in E. L.Richards application Ser. No. 471,740, filed May 20, 1974, thedescription of the relay is limited to the parts that are essential tooperation of the invention disclosed herein.

The relay includes multiple bi-metals 71, bi-metal heaters 73, a crossbar 75, a position adjusted trip lever ln the latched position theoverload protection mechanism'does not prevent operation of the switchin a normal manner between on and off positions during vnormal currentconditions.

'fWhat is claimed is:

l. A circuit interrupting device comprising relatively movable contactmeans and means releasable to effect 'automatic opening of said contactmeans, operating means for moving the contacts between open and closedpositions and comprising a releasable arm movable between latched andunlatched positions, a latch l'everoperable to effect unlatching of thereleasable arm, a retainer plate effective to releasably retain thelatch lever in the latched position, a trip device comprising a tripplate and bi-metal means for activating the trip plate in response toexcessive currents, the trip plate: being operatively connected to theretainer plate to move the retainer plate to the unlatched position, andthe retainer plate being spring-biased in the latched position with thelatch lever and including an extension engageable with the latch leverwhen in the unlatched i. to maintain the latch lever in a relatchingposi- 2. The circuit interrupting device of claim 1 in whichthe-extension comprises a portion extending toward the latch lever.

{3. The circuit interrupting device of claim 2 in which the latch leveris a first class lever, and the latch lever comprising one latching endportion latchingly engageable with the retainer plate and a second endportion ei'rgageable with said extension of the retainer plate.

4. The circuit interrupting device of claim 3 in which the retainerplate is a first class lever comprising a latchin gsurface engageablewith said one latching end portion.-

The circuit interrupting device of claim 3 in which said second endportion comprises a latching surface forfretaining the releasable arm inthe latched position.

1. A circuit interrupting device comprising Relatively movable contactmeans and means releasable to effect automatic opening of said contactmeans, operating means for moving the contacts between open and closedpositions and comprising a releasable arm movable between latched andunlatched positions, a latch lever operable to effect unlatching of thereleasable arm, a retainer plate effective to releasably retain thelatch lever in the latched position, a trip device comprising a tripplate and bimetal means for activating the trip plate in response toexcessive currents, the trip plate being operatively connected to theretainer plate to move the retainer plate to the unlatched position, andthe retainer plate being spring-biased in the latched position with thelatch lever and including an extension engageable with the latch leverwhen in the unlatched position to maintain the latch lever in arelatching position.
 2. The circuit interrupting device of claim 1 inwhich the extension comprises a portion extending toward the latchlever.
 3. The circuit interrupting device of claim 2 in which the latchlever is a first class lever, and the latch lever comprising onelatching end portion latchingly engageable with the retainer plate and asecond end portion engageable with said extension of the retainer plate.4. The circuit interrupting device of claim 3 in which the retainerplate is a first class lever comprising a latching surface engageablewith said one latching end portion.
 5. The circuit interrupting deviceof claim 3 in which said second end portion comprises a latching surfacefor retaining the releasable arm in the latched position.